All-trans retinoic acid restores gap junctional intercellular communication between oral cancer cells with upregulation of Cx32 and Cx43 expressions in vitro

Abstract

Objective: All-trans retinoic acid (ATRA) has been demonstrated to inhibit tumor growth by restoration of gap junctional intercellular communication (GJIC) via upregulation of connexin (Cx) expression in some solid tumors. However, the relationship between ATRA and GJIC remains unclear in oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the effect of ATRA on the GJIC function of OSCC. Study design: We measured the effects of ATRA on the viability and cell cycle distribution of SCC9 and Tca8113 OSCC cells. The GJIC function was observed using the scrape-loading dye transfer technique, and the mRNA and protein levels of Cx32 and Cx43 were detected by qRT-PCR, Western blot, and immunofluorescence assays. Results: ATRA inhibited the growth of OSCC cells in a dose- and time-dependent manner (P <0.05) and caused cell cycle arrest. ATRA-treated cells showed a 2.69-fold and 2.06-fold enhancement of GJIC in SCC9 and Tca8113 cells, respectively (P <0.05). Moreover, ATRA induced upregulation of Cx32 and Cx43 at both the mRNA and protein levels in OSCC cells. Conclusion: Our results indicated that restoration of GJIC via enhanced Cx32 and Cx43 expression might serve as a novel mechanism for the anti-tumor effect of ATRA in OSCC. Key words:All-trans retinoic acid, oral squamous cell carcinoma, connexin, gap junctional intercellular communication.

Porphyromonas gingivalis lipopolysaccharide induces over production of CC chemokine ligand 2 via toll‐like receptor‐4 in oral lichen planus

“…20 μL of MTT solution (Merck KGaA, Darmstadt, Germany) was added to each well and incubated for 4 hours at 37°C and then 150 μL of dimethylsulfoxide (DMSO; Merck, Darmstadt, Germany) was added. Absorbance was measured by automated microplate reader (Thermo Fisher Scientific, Waltham, MA, USA) at 490 nm …”

All‐trans retinoic acid exposure increases connexin 43 expression in cumulus cells and improves embryo development in bovine oocytes

“…Previous research has shown that exposure to all‐trans retinoic acid (ATRA) results in the increased expression of CX43, and subsequent increased gap junctional intercellular communication (GJIC), in multiple cell types including human leukemic bone marrow stromal cells, human oral cancer cells, and canine primary lens epithelial cells (Liu et al, ; Long et al, ; Wang et al, ). CX43′s structure plays an important role in its regulation by the cell, with a long cytoplasmic C‐terminal tail that contains several phosphorylation sites (Solan & Lampe, ).…”

“…Previous research has shown that exposure to all-trans retinoic acid (ATRA) results in the increased expression of CX43, and subsequent increased gap junctional intercellular communication (GJIC), in multiple cell types including human leukemic bone marrow stromal cells, human oral cancer cells, and canine primary lens epithelial cells (Liu et al, 2015;Long et al, 2010;Wang et al, 2013).…”

Liganded retinoic acid X receptor α represses connexin 43 through a potential retinoic acid response element in the promoter region

“…RA activates or represses target genes through the activation of two members of the nuclear receptor super family, retinoic acid receptors and retinoid X receptors (RXRs), binding to the retinoic acid response element (RARE) in target genes (14)(15)(16). In some cancer studies (17)(18)(19), RA has been found to alter the phosphorylation status of the Cx43 protein. Only a few studies have demonstrated the regulation relationship between RA and Cx43 in heart development (20), and the phosphorylation status is not a main cause of heart defects (10).…”